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Chapter 7 Alloy Oxidation III: Multiphase Scales
CHAPT ER
7 Alloy Oxidation III: Multiphase Scales
Contents
7.1. Introduction 7.2. Binary Alumina Formers 7.2.1 The Ni–Al system 7.2.2 The Fe–Al system 7.3. Binary Chromia Formers 7.3.1 The Ni–Cr and Fe–Cr systems 7.3.2 Transport processes in chromia scales 7.4. Ternary Alloy Oxidation 7.4.1 Fe–Ni–Cr alloys 7.4.2 Ni–Pt–Al alloys 7.4.3 Ni–Cr–Al alloys 7.4.4 Fe–Cr–Al alloys 7.4.5 Third-element effect 7.5. Scale Spallation 7.5.1 The sulfur effect 7.5.2 Interfacial voids and scale detachment 7.5.3 Reactive element effects 7.6. Effects of Minor Alloying Additions 7.6.1 Silicon effects 7.6.2 Manganese effects 7.6.3 Titanium effects 7.6.4 Other effects 7.7. Effects of Secondary Oxidants 7.8. Status of Multiphase Scale Growth Theory References
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7.1. INTRODUCTION Practical heat-resisting alloys have multiple components (Tables 5.1 and 9.1), nearly all of which are susceptible to oxidation in a wide range of environments. When these alloys are exposed at high temperatures, an initial, transient period of reaction in which all alloy components oxidize, is followed by a steady-state reaction. The rapid development of a corrosion-resistant, steady-state scale
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7 Alloy Oxidation III: Multiphase Scales
Contents
7.1. Introduction 7.2. Binary Alumina Formers 7.2.1 The Ni–Al system 7.2.2 The Fe–Al system 7.3. Binary Chromia Formers 7.3.1 The Ni–Cr and Fe–Cr systems 7.3.2 Transport processes in chromia scales 7.4. Ternary Alloy Oxidation 7.4.1 Fe–Ni–Cr alloys 7.4.2 Ni–Pt–Al alloys 7.4.3 Ni–Cr–Al alloys 7.4.4 Fe–Cr–Al alloys 7.4.5 Third-element effect 7.5. Scale Spallation 7.5.1 The sulfur effect 7.5.2 Interfacial voids and scale detachment 7.5.3 Reactive element effects 7.6. Effects of Minor Alloying Additions 7.6.1 Silicon effects 7.6.2 Manganese effects 7.6.3 Titanium effects 7.6.4 Other effects 7.7. Effects of Secondary Oxidants 7.8. Status of Multiphase Scale Growth Theory References
315 316 316 322 326 326 328 330 330 331 334 336 338 341 342 343 344 347 347 350 350 351 352 355 356
7.1. INTRODUCTION Practical heat-resisting alloys have multiple components (Tables 5.1 and 9.1), nearly all of which are susceptible to oxidation in a wide range of environments. When these alloys are exposed at high temperatures, an initial, transient period of reaction in which all alloy components oxidize, is followed by a steady-state reaction. The rapid development of a corrosion-resistant, steady-state scale
315